> Decimal is nice but the problem determines the base unit size.

> One base unit for the metric system was 1/10,000 the diameter of the
> Earth. I think the divisor is correct. A completely usless base unit.

But it is as good as any, it doesn't matter wether it's cubits, feet, meters, what ever. It's just a place to start. You get your base unit and you change the scale it by adding a prefix. For example: 1 centimeter=1/100th of a meter, 1 millimeter= 1/1000th of a meter, 1 micrometer 1/1000 000 of a meter. It's the same wether you're dealing in meters, litres, or grams, they all inter-relate and this makes equations easy to work out (for example 1 liter of water weighs 1 kilogram @ 20 degrees centigrade), especially in a chemistry lab where your dealing with moles/liter etc.

> A more rational base unit could have been chosen. Perhaps the smallest
> useful division on a measuring instrument - .01" or 1/4mm for a
> 10" ruler (a 10" ruler would be 1000 units) or .005'
> (1/16")for a 200' tape (a 200' tape would be 100,000 units).

But then when you want to measure 1000s of miles the numbers get a bit unwieldy, with the metric system you just change your units (scale) and you are still dealing with realatively small numbers (less than a thousand)

> I personally use decimals for everything. I change my base unit for
> diferent problems. For long distances hours of travel. For distances
> between 10' and 1000' a 100' tape divided into .01' works well. For boat
> building distances a tape divided into .01" works well. There is no
> need to convert.

This is the beuty of the system, you can write or equate large numbers without getting muddled up, as long as you keep your units straight. And converting between these units is kept simple.

> The world will not go metric because no base units are near the correct
> size for all applications and few people really have any need to convert.

The world of science allready HAS gone metric, the guys who make your epoxy should all be using the metric system to work-out their chemistry.